This invention is directed to an irrigation sprinkler control system wherein a clock controls the day and time of day for sprinkling. A circuit responsive to soil moisture is connected serially between the clock and the solenoid operated valve to prevent irrigation when moisture is adequate.
Irrigation is needed in many arid areas for supplying water to architectural vegetation. Greenery is often planted around homes, commercial buildings and apartment developments to provide an attractive outdoor appearance for them. In order to minimize the manual labor of such irrigation and to avoid loss of plants when irrigation is forgotten, clocks are often used to control electrically actuated valves which supply water to the irrigation system. Such clocks have been developed to a point where one or more days of the week can be selected for sprinkling. Furthermore, the time of day and duration of sprinkling can also be selected. Such clocks sometimes have a plurality of terminals which can be connected to different water control valves for the control thereof. Such terminals are often referred to as stations. The clock usually sequentially energizes the stations, and the clock can be adjusted so that each station has its own individual adjustment of on time. In this way, irrigation of a number of different areas, each served by a station and a sprinkler valve, can be employed to deliver water to these areas in accordance with the program determined by the clock and independent of ground moisture. It would be desirable to conserve water by limiting the delivery of irrigation water when the ground moisture is adequate.